Current methods of locating subsurface ore bodies involve collecting soil samples from a number of locations across a prospective site and sending those samples for laboratory analysis to identify the potential for sub-surface ore deposits. Aerial surveys of the selected geographical area may also be conducted to assist in identifying likely deposit sites.
Known ways of collecting soil samples are labour-intensive and time-consuming, with significant potential for human error in the correct identification and accurate locating of soil samples across a site, as well as a risk of contamination of the samples. Transportation of soil samples to a laboratory is likewise expensive and fraught with the same potential for human error, as well as the protracted time in getting the samples from the site to a laboratory for analysis, analyzing each sample using a variety of instrumental techniques and more traditional techniques such as fire assay and then returning the results. Typically a period of several days or even weeks is needed to complete the analysis of all of the samples and return the results. Most analytical techniques involve the use of either mineral acid extractions, or fusion followed by spectrometric analysis. Fire assay procedures involve fusion for the sample with collection for gold and certain precious metals in a lead button, this button is then cupelled and either parted to remove silver and weighed or dissolved in mineral acid and subjected to spectrometric or spectrophotometric analysis for quantitation of the recovered precious metals. In more recent years, partial chemical leaches have also increasingly been used. These are based around the removal of a labile “coating” or a specific type of adsorbed chemical compound from a bulk soil matrix and in this way isolating the recently emplaced hydromorphic anomaly which, at the surface indicates the presence of deep or blind mineralization at depth. However, identification of hydromorphic anomalies is extremely difficult due to the extremely low concentration of hydromorphically-imposed ions compared to background levels of elements present in “background” soils or sediments. It has thus been found desirable to provide a method, system and apparatus to improve identification of, or to determine presence of, elements or compounds of interest in soil samples by detection of hydromorphic anomalies. The ability to determine the presence of hydromorphically emplaced anomalies above buried or blind ore bodies and in areas that are geochemically sterile as a result for thick and/or high iron content overburden opens up enormous areas of the world where exploration has heretofore been impractical, with particular reference to southern hemisphere countries such as Australia, South Africa, India and South American countries, for geochemical exploration. In addition, the fast and effective delineation of buried mineralization opens up the next generation of geochemical exploration through the possibility of determining the presence of mineralization that is not amenable to discovery through more traditional means of both geochemical and geophysical exploration.
One known system is disclosed in U.S. Pat. No. 4,056,969 to Barringer Research Limited. That document discloses a method and apparatus for geochemical exploration for mineral deposits in which particles contained on the surface of the earth are collected and analysed. A surface dust traverse is carried out whereby a land based vehicle, such as a truck, or aerial vehicle, such as a helicopter, trails a tube behind it over an area of land to be surveyed for presence of mineral deposits. Dust from the top millimeter of surface soil is collected by suction up the tube for analysis approximately every 105 meters. The background section of U.S. Pat. No. 4,056,969 discusses previous practices of sampling soil from 10 centimeters to 1 meter below the surface and the top 1 cm to 2 cms of soil are discarded to avoid contamination from animals or deposition of wind swept matter into the sampling area. U.S. Pat. No. 4,056,969 focuses on taking rapid samples from the very surface (top 1 millimeter) in order to identify by analysis the presence of micro-organisms that may indicate the presence of hydrocarbon deposits, or sampling from the same 1 milimeter or from vegetation to identify the presence of particulate materials. Even on water the method and system of U.S. Pat. No. 4,056,969 is only sampling the very surface of the water for particulates and micro-organisms as indicators of the presence of minerals or hydrocarbon deposits. There are obvious problems with such a sampling regime. Wind blown particulates can contaminate an area, particularly if there are mineral sands or other ore bodies being worked or transported within the region. Likewise, animals, such as farmed animals (cattle, sheep, goats etc.) or numbers of wild animals (kangaroos, horses, camels) using the area prior to sampling can contaminate the area. This can lead to erroneous analysis results.
U.S. Pat. No. 4,056,969 also only proposes the sampling and analysis of relatively large particles. Particles are sucked up the tube; however, particles above 200 micron (μm) are sieved out by a mesh screen. A jet spaced 2-3 cm away from a sampling tape allows large relatively heavy particles from within the 200 micron sample to impact the tape to capture a sample. Smaller, lighter particles below 50 micron size do not make it across the 2-3 cm space and are blown away from the tape as rejected material. Consequently, the system and method of U.S. Pat. No. 4,056,969 is only sampling particle sizes of between 200 micron and 50 micro size from the at surface soil. Such particles can be wind blown surface particles from another area, or may be carried in or deposited by vehicle movements or animals traversing the land. Such particles would not form part of the original soil surface but would be sampled and analsyed as if they were. U.S. Pat. No. 4,056,969 does not teach or disclose distinguishing original soil particles from foreign soil particles, and does not sample below the very surface of the soil, which could lead to erroneous results.
The collection tape used in U.S. Pat. No. 4,056,969 relies on an adhesive and an additional plastic cover tape to hold and protect the collected samples on the tape. The cover tape is rolled up with the collection tape once samples are blown onto the collection tape. This requires two tapes that must be aligned and rolled up together. There is a risk of one tape not properly covering the other, or the tapes not rolling up together. Either way, collected samples are at risk of contamination or damage.
Furthermore, the tube trailed behind the vehicle can get caught up as it is drawn across the surface, particularly on uneven or rocky ground or where there is vegetation. This can endanger the vehicle, particularly if a helicopter is used.
The present invention was developed with the aforementioned in mind. It provides a more efficient system, apparatus and method for identifying indicators of the presence and/or location of subsurface ore bodies that is less susceptible to the problem of human error or delay found in known systems.
References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.